I want to get a key as input and a comparison of key value in if condition

It shows KeyError: ('Black in Black', 8.5)

album_rating={"Black in Black":8.5,"Believer":6,"SmackTac":7,"You":9}
a=(input("Enter the name:"))

For a in album_rating.items():
    if(album_rating[a]>8):
     print("This album is Amazing!")
    else:        
     print("Try a different album")
print("Welcome")

There a couple of things which need fixing here. Firstly you name your input variable a but then use that to loop over your dictionary.

Secondly dict.items() returns a list of key value pairs e.g.

[('Black in Black', 8.5), ('Believer', 6), ('SmackTac', 7), ('You', 9)]) so a will never be found in the dictionary because you are comparing a string to a list hence the KeyError.

If you want to loop over the keys of a dictionary specifically then you should use dict.keys(). Alternatively you can use a try-except block to catch any KeyErrors.

album_rating={"Black in Black":8.5,"Believer":6,"SmackTac":7,"You":9}
a=input("Enter the name:")

try:
    album = album_rating[a]
    if(album_rating[a]>8):
        print("This album is Amazing!")
    else:        
        print("Try a different album")
except KeyError:
    print ("Album does not exist")

OR

album_rating={"Black in Black":8.5,"Believer":6,"SmackTac":7,"You":9}
a=input("Enter the name:")

if a in album_rating.keys():
    if(album_rating[a]>8):
        print("This album is Amazing!")
    else:        
        print("Try a different album")
else:
    print ("try again")